Effects of concentrate supplementation strategies during the transition period and milking frequency in early lactation on seasonal winter-calving organic dairy cows

Abstract At the start of lactation, a severe energy deficiency can have negative impacts on dairy cows’ performance and health. The objective of this 3 × 2 factorial study was to compare the effects of three concentrate (C) build-up strategies during transition period (C-21; C1; C+21) and two milking frequencies (M) during 1st week of lactation (once vs. twice-daily milking; M1 vs. M2) on feed intake, milk yield, energy supply, body weight, body condition score, metabolic status, health, and fertility parameters. During the three years of study, data were collected for 66 transition periods (N) from 37 individual animals (21 Holstein Friesian (HF) and 16 Austrian dual purpose Simmental animals (SI); 8 primiparous cows in each breed). Four weeks (1st Nov., ±57.2 days) before expected calving date the animals were allocated randomly (balanced for parity, breed, calving date, insemination index in the previous breeding season and genetic merit) to one of three concentrate supplementation strategies (C) during the transition period (C-21; C+1; C+21; N=22 group−1). Within these three C groups, half of the cows were either milked once (M1) or twice (M2) during 1st week of lactation, and from 8 DIM onwards all cows were milked twice a day. All animals were offered a high-quality forage basal diet comprising hay and grass silage from four weeks before expected calving date until 98th days in milk (DIM). In group C-21 the concentrate supplementation started 21 days (-21 days) before expected calving date and was increased (DIM -21 to -15) from 1.8 kg dry matter (DM) to 2.6 kg DM (DIM -14 to 1) until parturition; during the first 14 DIM concentrate supplementation was daily increased by 0.26 kg DM cattle−1 from 2.6 to 5.9 kg DM and from 15 DIM onwards concentrate supply depended on actual milk yield of the individual cow. In group C+1 no concentrate was fed pre-partum, and from lactation day 1 onwards the same concentrate building up strategy and allocation was made as described for group C-21. In group C+21 the concentrate supplementation did not start until 21 DIM and from this point on the same concentrate build-up-strategy was implemented as described for group C+1, but with each phase delayed by 21 days. Pre-calving feed and net energy intake (NEL) as well as net energy balance (EB) was significantly higher in C-21 compared to groups C+1 and C+21. During the first seven weeks of lactation C+21 groups (P